Your MH jacks may have a grease zert at the seal on the jack housing. I found quite a build-up of muck at the seal the first time I cleaned the jack rams. You may want to wipe off the zert and give each a few shots of approved grease before cleaning the ram. Then, shoot the seal area with some silicone spray and using multiple paper towels and your thumbnail, clean the seal area. Finally, shoot the entire ram with the spray and clean it while trying to remove as much of the silicone spray as possible.
I throw down a strip of carpet and take under the grease gun, spray, paper towel roll and an empty plastic grocery bag for the used paper towels. It goes pretty quick.